I figured this question should be a new topic as it is specific to the speed variable.

I'm in the middle of Tutorial 2 on youtube, and the speed function and it's scales see weird.

What are the units of the speed? px/s? If it is an absolute scale, multiplying it by 150 makes some sense. Or is it another normalized value, such as some maximum speed? If so, how is that maximum speed determined?

This came about because, in order for it to be appropriately inverted, multiplying the original value by 150 must result in a number that is less than 1 (input A in the Sub function) in order for you to still get a positive number. That being the case, the range must be huge.